The present invention relates to the production of metals and alloys using the general method disclosed in U.S. Pat. Nos. 6,409,797; 5,958,106; and 5,779,761, all of which are incorporated herein, and preferably a method wherein titanium or an alloy thereof is made by the reduction of halides in a flowing liquid stream of reducing metal.
Although the process and system hereinafter described pertains to titanium base alloys, it is applicable to a wide variety of alloys, wherein a superheated halide is used to vaporize a liquid halide to form an alloy in which the constituents include the superheated halide and in the liquid halide.
The Armstrong Process is defined in the patents cited above and uses a flowing liquid metal stream into which is introduced a halide vapor. The liquid metal stream may be any one or more of the alkali metals or alkaline earth metals or mixtures thereof, however, the preferred metal is sodium because of its availability, low cost and melting point, permitting steady state operations of the process to be less than 600° C. and approaching or below 400° C. Preferred alternates are potassium or NaK while Mg and Ca are preferred alkaline earth metals. One very important commercial aspect of the Armstrong Process as disclosed in the above-referenced and incorporated patents is the ability to make almost any alloy wherein the constituents can be introduced as vapor into the flowing liquid metal. For titanium and its alloys, the most common commercial alloy is what is known as 6-4 alloy, that is 6% percent by weight aluminum, 4% by weight vanadium with the balance titanium, the ASTM B265 classifications for Ti are set forth in Table 1 hereafter (Class 5 is alloy 6-4). The ASTM 265 classification for commercially pure (CP) titanium is Class 2.
TABLE 1Chemical RequirementsComposition %GradeElement12345678910Nitrogen max0.030.030.050.050.050.050.030.020.030.03Carbon max0.100.100.100.100.100.100.100.100.100.08HydrogenB max0.0150.0150.0150.0150.0150.0200.0150.0150.0150.015Iron Max0.200.300.300.500.400.500.300.250.200.30Oxygen max0.180.250.350.400.200.200.250.150.180.25Aluminum. . .. . .. . .. . .5.5 to4.0 to. . .2.5 to. . .. . .6.756.03.5Vanadium. . .. . .. . .. . .3.5 to. . .. . .2.0 to4.53.0Tin. . .. . .. . .. . .. . .2.0 to. . .. . .. . .. . .3.0Palladium. . .. . .. . .. . .. . .. . .0.12 to. . .0.12 to. . .0.250.25Molybdenum. . .. . .. . .. . .. . .. . .. . .. . .. . .0.2 to 0.4Zirconium. . .. . .. . .. . .. . .. . .. . .. . .. . .. . .Nickel. . .. . .. . .. . .. . .. . .. . .. . .. . .0.6 to 0.9ResidualsC.D.E.0.10.10.10.10.10.10.10.10.10.1(each), maxResidualsC.D.E0.40.40.40.40.40.40.40.40.40.4(total) maxTitaniumFremainderremainderremainderremainderremainderremainderremainderremainderremainderremainderAAnalysis shall be completed for all elements listed in this Table for each grade. The analysis results for the elements not quantified in the Table need not be reported unless the concentration level is greater than 0.1% each or 0.4% total.BLower hydrogen may be obtained by negotiation with the manufacturer.CNeed not be reported.DA residual is an element present in a metal or an alloy in small quantities inherent to the manufacturing process but not added intentionally.EThe purchaser may, in his written purchase order, request analysis for specific residual elements not listed in this specification. The maximum allowable concentration for residual elements shall be 0.1% each and 0.4% maximum total.FThe percentage of titanium is determined by difference.
In making 6-4 alloy, one of the problems is the instability of VCl4. VCl4 is commonly transported as liquid vanadium tetrachloride, but liquid vanadium tetrachloride is unstable and decomposes to vanadium trichloride, the rate of decomposition being temperature dependent. Vanadium trichloride is less desirable as a feedstock for the Armstrong Process because it has a much higher melting and boiling point than vanadium tetrachloride. Moreover, decomposition of liquid tetrachloride to solid trichloride in a vanadium tetrachloride boiler adversely affects boiler performance due to the solids build up resulting in poor boiler pressure control, premature failure of boiler heaters, line plugging, loss of usable feedstock and excessive maintenance.